Conventional powered roller conveyors employ support shafts which extend across the width of the conveyor and support coaxially aligned rollers adjacent the opposite side frames. Such conveyors simplify the driving of the coaxially aligned pairs of rollers since a single shaft can drive both rollers of the pair. However, such conveyors can be used only on selected types of loads since the entirety of the load must be positioned above the shaft.
The use of through shafts also imposes greater restraints on the use and particularly the adaptability of the conveyor in terms of its width so as to permit the conveyor to accommodate different types of loads.
To overcome the disadvantages associated with through-shaft type roller conveyors, cantilevered-shaft roller conveyors are also known. In conveyors of this latter type, the rollers are supported on cantilevered shafts which project inwardly from the side frames, whereby the coaxially aligned pairs of rollers define an open region therebetween.
While known cantilevered-shaft roller conveyors do overcome some of the disadvantages associated with through-shaft roller conveyors, nevertheless known cantilevered-shaft roller conveyors have themselves possessed features which have been less than desirable. For example, such conveyors typically employ drive shafts (commonly referred to as "line shafts") which extend longitudinally of the conveyor and are typically drivingly connected to the roller units through gears, chains and the like. These line shafts are typically disposed exteriorly of the side frames, whereby the roller units are supported on shafts which project through the side frame and have a drive member such as a gear on the outer end, and the drive roller on the inner end. Such arrangements typically result in rather complex driving connections and roller units, and in addition position rotatable driving members exteriorly of the frame whereby they obstruct access to the sides of the conveyor and are undesirably positioned relative to operating personnel.
Many of the known conveyors have also employed roller units which are of substantial structural complexity in view of the number of parts and bearings required, and which have resulted in significantly complex drive arrangements and connections. Such units also have typically permitted solely positive driving of the rollers, or frictional driving of the rollers, but have not readily permitted the user to select one or the other without requiring some significant and complex structural rearrangement.
Examples of prior art conveyors are illustrated by the following: U.S. Pat. Nos. 4,185,735, 4,844,231, 4,884,676, 4,930,613; French Patent No. 81 12796; Japanese Patent Publications 1-285515 and 61-7111; and Publication WO 91/09793. These publications illustrate both cantilevered-type and through-shaft roller conveyors which possess disadvantages of the type discussed above.
Accordingly, it is an object of this invention to provide an improved cantilevered-type roller conveyor which overcomes many of the disadvantages associated with known conveyors of this general type.
More specifically, in the improved cantilevered-shaft type roller conveyor of this invention, the roller units as cantilevered inwardly from the side frames of the conveyor are of an improved and simplified construction in that a sleevelike roller member is supported directly on and surrounds a drive member, the latter being rotatably supported on a cantilevered shaft which is secured to and projects inwardly from the side frame. The drive member, in a preferred embodiment of the conveyor, has a bevel drive gear which is fixedly and preferably integrally formed on an inner free end thereof, which drive gear is driven from a mating bevel gear secured to a rotatable line shaft which is positioned inside the respective side frame and extends longitudinally of the conveyor. The drive member is preferably constructed of a suitable bearing material, such as sintered metal, to permit it to function both as a driving gear member and as a bearing to permit direct rotatable support of the sleeve roller member.
In the improved conveyor of this invention, as aforesaid, the drive member and sleeve roller member also preferably have a selectable coupling arrangement therebetween which, depending upon the axial orientation of the sleeve roller member relative to the drive member, permits either direct and positive driving of
the sleeve roller member or frictional driving thereof so as to permit either positive stopping of the roller member or overrunning thereof, depending upon the selected mounting orientation of the roller member.
With the preferred cantilevered-type roller conveyor of this invention, as aforesaid, loads can be conveyed along the conveyor which have a size or geometry such as to protrude into an open region defined between the sidewardly-spaced roller units, and the loads can be positively stopped at a precise location when the sleeve roller members are positively driven from the drive members, or alternatively the sleeve roller members can be permitted to rotate relative to the drive members, such as to permit overrunning. In addition, the line shafts for driving the rollers are positioned interiorly of the side frames so as to maximize accessibility and clearance exteriorly of the side frames. The roller units also minimize the number of parts, including bearings, to simplify the overall construction, assembly and repair if necessary.